Al0.35Ga0.65As/InGaP heterojunction solar cell based on temperature-graded growth

Abstract The p-Al 0.35 Ga 0.65 As/n-InGaP heterojunction solar cells are promising competitors compared with conventional InGaP or AlGaAs solar cells as the heterogeneous combination can overcome the demerits of each material. However, InGaP has an optimized growth temperature much lower than that of AlGaAs in metal-organic vapor phase epitaxy (MOVPE) growth. Therefore, a challenge arises from oxygen contamination at the hetero-interface during temperature adjustment for obtaining MOVPE-grown high-quality p-AlGaAs/n-InGaP heterojunction. Here we report that a temperature-graded layer (TGL) of AlGaAs can solve the issue of growth temperature mismatch, and significantly improve the voltage performance of AlGaAs/InGaP solar cells. Absolute electroluminescence measurement and atomic force microscopy confirmed a smooth interface with less non-radiative recombination after TGL was applied. The temperature-graded growth is verified able to improve the AlGaAs/InGaP interface quality and provides a scalable method for AlGaAs-based heterogeneous growth.